TUESDAY, Aug. 4 (HealthDay News) -- Having coronary artery disease (CAD) may have a larger sustained effect on the risk of developing major depression than vice-versa, according to research published in the August issue of the Archives of General Psychiatry.

Kenneth S. Kendler, M.D., of the Virginia Commonwealth University School of Medicine in Richmond, and colleagues analyzed data from 30,374 Swedish twins. Information on major depression was collected during interviews with participants, and data on CAD was obtained from a Swedish database of hospital discharge diagnoses.

The researchers found that the lifetime association between major depression and CAD was relatively small (odds ratio, 1.3). However, in time-dependent analyses, the onset of CAD was associated with a 2.83 hazard ratio for major depression in the same year, and a 1.75 hazard ratio in following years. If subjects developed major depression, the hazard ratio for CAD onset was 2.53 that year, but was just 1.17 in following years.

"In conclusion, although the major depression-CAD relationship across the lifespan is modest, time-dependent models reveal stronger associations. The sustained effect of CAD onset on major depression risk is much stronger than vice versa. The effect of major depression on CAD is largely acute, and the longer term effects are apparently mediated via depressive recurrence. When examined separately, in men, environmental effects, which are often acute, have a large role in major depression-CAD comorbidity, whereas in women, chronic effects, which are in part genetic, are more important," the authors conclude.

Abstract
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